Mashable

In the early 1920s, the Ku Klux Klan was at the peak of its membership, numbering 3 million strong. The growth of the hate group was fueled by the 1915 release of the silent film Birth of a Nation, which portrayed members as heroes, coinciding with the widespread xenophobia following the devastation of World War I.

The KKK's hatred was directed not only against black people, but also against European Catholic and Jewish immigrants flocking to the U.S. after the war.

In 1925 and 1926, the Klan descended on Washington, D.C. for two massive marches.

City officials fiercely debated whether to allow a white supremacist organization known for lynchings, violence and terror to parade around the U.S. capital. The decision was ultimately made to let them march, albeit without their signature masks.

The so-called “konklave” drew upwards of 50,000 Klansmen, who marched through the city in a chilling display.